A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-07 12:25:00 -04:00
Code Issues Projects Releases Packages Wiki Activity

FROMLIST: mm/madvise: replace ptrace attach requirement for process_madvise

Browse source 
Mot-CRs-fixed: (CR)
process_madvise currently requires ptrace attach capability.
PTRACE_MODE_ATTACH gives one process complete control over another
process. It effectively removes the security boundary between the
two processes (in one direction). Granting ptrace attach capability
even to a system process is considered dangerous since it creates an
attack surface. This severely limits the usage of this API.
The operations process_madvise can perform do not affect the correctness
of the operation of the target process; they only affect where the data
is physically located (and therefore, how fast it can be accessed).
What we want is the ability for one process to influence another process
in order to optimize performance across the entire system while leaving
the security boundary intact.
Replace PTRACE_MODE_ATTACH with a combination of PTRACE_MODE_READ
and CAP_SYS_NICE. PTRACE_MODE_READ to prevent leaking ASLR metadata
and CAP_SYS_NICE for influencing process performance.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Link: https://lore.kernel.org/lkml/202101111033.2D03EA97@keescook/T/#u

Test: built and flashed kernel
Bug: 153444106
Signed-off-by: Edgar Arriaga <edgararriaga@google.com>
Change-Id: I3624a8b0697d70f23587c1dcb746ba753c301f45
Reviewed-on: https://gerrit.mot.com/2765787
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Zhangqing Huang <huangzq2@motorola.com>
Reviewed-by: Huosheng Liao <liaohs@motorola.com>
Submit-Approved: Jira Key
This commit is contained in:
Edgar Arriaga 2021-01-11 15:19:48 -08:00 • committed by Xiaojun Ji
commit a90824b3cb
1 changed files with 13 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

14
mm/madvise.c
View file

@ -1267,12 +1267,22 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd,
goto release_task;
}
mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS);
/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
if (IS_ERR_OR_NULL(mm)) {
ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
goto release_task;
}
/*
* Require CAP_SYS_NICE for influencing process performance. Note that
* only non-destructive hints are currently supported.
*/
if (!capable(CAP_SYS_NICE)) {
ret = -EPERM;
goto release_mm;
}
ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
if (ret >= 0) {
size_t total_len = iov_iter_count(&iter);
@ -1282,6 +1292,8 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd,
ret = total_len - iov_iter_count(&iter);
kfree(iov);
}
release_mm:
mmput(mm);
release_task:
put_task_struct(task);